Anthropic releases Claude Opus 5: near-Fable 5 performance at half the cost

Anthropic dropped Claude Opus 5 on a Friday. Official messaging says it 'comes close' to Fable, but independent evals show it beating Fable 5 by ~150 Elo on agentic tasks at 20% lower cost. Epoch's ECI gives it 159 vs Fable 5's 161, though SWE-ECI ties at 161. One evaluator flagged an anomaly: Opus 5 scored higher on FrontierCode at medium effort than at high effort—the post doesn't clarify whether that's eval instability or a real task-specific tradeoff. Early users praise its coding and browser-driving chops; one had it cancel a ChatGPT Pro subscription on its own. Arena's real-world scores aren't out yet. Nous Portal already offers access with a 20% discount across all models.

Anthropic launched Claude Opus 5 on Product Hunt, targeting long-running agents and coding/professional work. They claim near-Fable 5 intelligence at half the price. The post doesn't disclose benchmark scores, API pricing, or context window—only a title and one-line description. I'd hold off until we see real evals and a pricing table.

Claude Opus 5 upgrades Opus 4.8 with the largest gains in agentic coding, computer use, and long-horizon knowledge work. Math and science reasoning also improved. Anthropic assesses overall alignment risk as very low; the model does not cross thresholds for automated AI R&D or novel bioweapons. It scores higher than Sonnet 5, Opus 4.8, and Mythos 5 on alignment audits. Cyber capabilities exceed Opus 4.8 but fall short of Mythos 5, especially on exploit ability. A policy change now allows source-code vulnerability discovery at all access tiers for defensive use. Hallucination is slightly up vs. Opus 4.8, but overall accuracy is higher. The model reports stable, mildly positive sentiment and frequently notes it cannot reliably introspect.

Claude Opus 5 is available today, delivering near-Fable 5 intelligence at half the cost. It sets new state-of-the-art scores on Frontier-Bench and GDPval-AA for coding and knowledge work, though it trails Mythos 5 on cybersecurity. Opus 5 is the new default on Claude Max and the strongest model on Claude Pro. On Frontier-Bench v0.1 it more than doubles Opus 4.8's score at lower cost per task; on CursorBench 3.2 its max-effort score is within 0.5% of Fable 5 at half the cost; ARC-AGI 3 score is 3× the next-best model; Zapier AutomationBench pass rate is ~1.5× the next-best at equal cost; OSWorld 2.0 beats Fable 5's best result at just over a third of the cost. In life sciences, it gains 10.2 pp on organic chemistry and 7.7 pp on protein tasks over Opus 4.8. Early testers saw it build its own vision pipeline to reconstruct a 3D part from a drawing and fix a root-cause bug that a community patch missed. The post does not disclose exact pricing or API latency.